I love my stepsister
by forbiddenlove123
Summary: Derek is in love with Casey but he doesn't want to be. Soon Derek realizes that Casey was the only girl for him and to make him forget about her, he starts to date kendra. PLease click here to see the whole summary.DASEY.
1. Chapter 1

_"I love my step-sister..."_

_Derek is in love with Casey but he doesn't want to be. Soon Derek realizes that Casey was the only girl for him and to make him forget about her, he starts to date kendra, but Casey gets jealous and she tells him how she feels towards him. they start to date, but what happens when they're secrets gets out? Will they be able to be together? or will they both be heart broken? This story is a tale about two undying lovers and their forbidden love. _

Casey stood there watching the moon shine with the stars though the window… it matched her eyes perfectly. They were both sparkling and beautiful. Derek knew saying this was wrong, especially since Casey was his step sister, but Derek couldn't help himself. It was like something was pulling him closer and closer to Casey.

"Derek!" Casey yelled!

"What?"

"Don't sneak up on me like that! God haven't you heard of privacy! God! You have some nerve!"

Casey pounded Derek's chest hard, but he didn't care… Derek smirked and chuckled

"Hey, sorry princess Casey…couldn't help but stare I mean you were standing there like an idiot."

"I guess it comes from living with you too long!"

"I'm sorry, what?"

He dropped his soda and grabbed Casey's wrists. Derek laughed. Casey tried to get away from Derek, but Derek was so much stronger than her.

"Let go! Derek!"

"Say please!"

Casey struggled to get her wrists away from Derek, but he wouldn't let go. Than suddenly she pulled her wrists away from Derek, pulling him on top of her. His face was 2 inches far from her face. Their lips touched (but they didn't kiss… just so you guys know.) Derek could feel her breathe and smell her natural body scent. She smelled like fresh strawberries.

"Um… Derek?"

"Yes?"

"Could you get off of me? I can't breathes anymore…"

"Oh. Sorry."

Derek got up and put his hand out.

"Need a hand sis?"

Casey slapped Derek's hand away from her.

"Not from you I don't, brother."

Derek smirked as Casey walked away.

Casey's room 

Casey locked her bedroom door. She jumped on her bed. She touched her lips and wondered.

"Did our lips just touched… NO stop! What are you thinking!? God all you need is a good night sleep. Yeah that's it!"

Casey Changed into her pajamas and went to bed.

Derek's room

Derek shut his bedroom door and got his headphones off his dresser. He went to his window and felt the breeze coming though the window.

"Our lips touched."

Derek smirked and chuckled. He looked at the window on his left side, which was Casey's window. Casey had turned her light off making it dim for Derek.

"Stop it Derek!"

Derek shut the window closed and went to bed himself.

The next morning, Casey got dressed for school. She went down stairs to the kitchen to get breakfast. Nora came rushing downstairs with George.

"Casey! I'm so glad you're awake! Do you mind waking up Derek and the others?"

"Why do I have to mom?"

"George and I have to go to work early today so please! Do this for me Casey please!"

"Fine"

"Thank you."

Nora kissed Casey on the cheek.

"Bye! Have a great day at school!"

George waved bye and they left.

Casey went upstairs to wake up everybody. She started with Lizzie.

"Lizzie, wake up!"

Lizzie woke up.

"Where's mom and George?"

"They had to leave for works early now get dressed."

Casey woke the other two up except… Derek.

"Derek, wake up!"

Casey shook Derek, but he wouldn't wake up. All he did was groan.

"Stop bothering me!"

"Then wake up already!"

Casey then pulled his sheets off of him and saw Derek in his underwear!

Casey Screamed! Derek looked down and he, also screamed himself. Casey ran out of the room and shut the door closed. Casey goes downstairs to the kitchen. Edwin and Lizzie look at each other than at Casey.

"What's wrong Casey?"

"What do you mean what's wrong? Nothings wrong!"

"You know as your little sister I can always tell when you're lying"

"What? I'm not-"

Than suddenly Derek comes in the kitchen. Casey and Derek look at each other than they looked away. Casey tries to change the subject.

"Hey Lizzie, Edwin could you guys take Marti to her school? Please!"

"Sure, Case. Come on Lizzie, Marti. Let's go to school."

They three of them went to school leaving Casey and Derek alone.

High school

"Hi Emily"

"Hi Casey"

"Hey you want to catch a movie tonight?"

"Oh sorry I have a date with Sheldon."

"Oh…"

Casey looked disappointed.

"Can we go watch a movie another time?"

"Sure. I got have to go the bell is going to ring."

Then Derek suddenly came in front of Casey. Sam was behind Derek.

"Move, Derek."

Casey slid to the left of Derek, but he blocked her. She moved to the right of him, but he blocked her there to. Casey got tired of his games.

"Derek! Move! I'm gonna be late!"

Then suddenly the bell rang. Derek smirked. He patted Casey on the shoulders and chuckled.

"Hope you have a nice day in school."

Casey opened her mouth. She had never been late for class! Today was the first day she was ever late for class! She wanted to kill Derek! No, she was going to kill him!

"Dude wasn't that a little harsh?"

"No, look Sam I know about you guys, but its over and you know that I like to annoy her. Plus I thought you guys broke up? Why care for her still?"

"Even though we broke up, it doesn't mean I can't care for her as a friend?"

Derek sighed and grabbed Sam's shoulders.

"Look Sam, I know your one of those sensitive guys that girls like Casey would love to date, but when you break up with a girl. You need to know when to let her go and obviously your not letting her go. It shouldn't be you who is still holding on to the girl it's the girl who should be thinking about you the whole time you hear?"

Sam looked at Derek. Sam pushed Derek's hands off his shoulders.

"Dude what you just said was totally a sexist comment."

Derek popped him collar.

"Who cares?"

They both walked to class.

At lunch time, Derek made a bet with Sam that he could get Mindy, the head cheerleader to buy him lunch. Sam knew she wasn't interested in Derek so he said "Your on!" When Derek left, Sam saw Casey sitting at a lunch table near him. He hesitated at first , but he, than he got up from his seat and walked towards Casey.

"Mind if I have a seat?"

Casey looked from her book and saw Sam.

"Uh…yeah, sure."

He took the seat.

"So…uh… what are you reading?"

"Nothing, its really just about Martin Luther King."

"Oh interesting."

It was in silence around that table.

"Sam...Uh… not to be rude or anything but what did you really come here for?"

"Well, the truth is… I just wanted to know if everything was cool between us? I mean after what happened?"

"Yeah I mean totally. Sam what happened between us is ancient history so you don't have to worry about it."

"Great!'

Derek came back to an empty table. He than, saw Sam talking with Casey and laughing with her. Derek was jealous. He couldn't stop wanting to kill Sam. Derek walked over to their table.

"I suggest you give me 15 dollars now."

"No way, you got it!"

"Yeah I got it!"

Derek showed Sam the lunch tray. Sam amazed, handed Derek 15 dollars. Casey scoffed.

"Made another girl buy you lunch?"

"Yeah… what's it to you?"

"Everything… you are the most obnoxious man I have ever met! Making girls buy you lunch… its called your own money!"

"Its called being generous"

Casey and Derek eyed each other. Sam had stopped the fighting.

"Uh… guys why don't you stop fighting for once huh? Come on."

They both looked away from each other.

"Come on Sam. Let's go back to our table so we don't have to bother the bookworm!"

The bell rang and school was over.

Casey got her homework and stuff from her locker. When she got out of school she saw Derek in front of the school yard. She went home first. Derek and Casey never went home together. She would always go home first, but today Derek walked with her.

"Hey klutzilla!"

Casey stopped and turned around.

"What?"

"Stop trying to hang around Sam."

"What? Ok first of all you are not the boss of who I hang out with nor Sam's boss! Second of all why do you care?"

"I don't care about you or who you hang out with, but Sam is my friend and I don't him to hanging out with you!"

"Why?"

"Because I don't want Sam to hang out with his ex-girlfriend. Once your finished with whoever you shall never and I mean never see her again! You hear me?"

"Oh my god that was the most stupidest thing I have ever heard of!"

Derek folded his arms.

"And how so?"

"Even if the relationship is over you can still be friends with that person!"

Derek scoffed.

"Yeah right."

Casey screamed! She walked away.

Macdonald and Venturi's house

Casey went upstairs to her room while Derek grabbed the remote to watch TV.

"What's with Casey?"

"I don't know why don't you ask your step-sister."

Edwin looked up the stairs. He shook his head.

"Rather not."

Lizzie came downstairs and took the remote from Derek.

"Lizzie I know your new in this house, so I'm going to act like you just didn't do that."

Derek tried to take the remote from her, but she was quick to take the remote farther from him.

"Guess you got guts. What do you want?"

"I want an apology to my sister!"

Derek and Edwin stayed silent for a moment than laughed hard. Lizzie looked puzzled.

"Why are you laughing? This is not funny!"

"Yes it is!"

"And why would this be funny?"

"Tell her Edwin."

"Oh Lizzie, Lizzie you see, this is Derek we're talking about. He does not and I mean DOES NOT apologies to anyone!"

Lizzie got down to her knees and begged.

"Please apologize to my sister!"

Derek looked down at her. He smirked.

"Let me ask you something. Why would you go though so much for _Casey_?"

"Because we're family."

Derek smirked and got up from his seat.

"Fine I'll apologize, but only this time!"

Derek went up to Casey's room.

"Knock, knock Guess who? Yes its your favorite brother, Derek Venturi!"

"Oh darn and I was hoping it was Edwin…"

Derek smiled and seat in her chair. He rolled towards Casey's bed where she was lying on.

"Listen I am here to say sorry… ok happy? See ya!"

Derek was about to get out of her room, but Casey stopped him.

"Derek! Why would you apologize to me? I thought you didn't apologize to anyone?"

Derek turned around.

"I guess because we're family…"

Derek had left her room. He stood out of her room and leaned on the door.

"_Why is my heart beating so fast? Could it be that I… NO! Derek Venturi does not and I repeat does not fall in love!"_

He walked to his room with a confused look…

As Edwin was walking past Derek's room, Derek grabbed Edwin's collar and pulled him into his room.

"Derek? What's wrong?"

"Ok, I am going crazy! I keep having these thoughts over this Ca… Cassandra, this new girl in my school and I don't like her, but she keeps coming into my head and I can't get rid of her! What should I do?"

"It is obvious you like her so go ask her out."

"Yeah I would but she's… a little different from my usual likes."

"What do you mean?"

"Well…"

Derek looked at Edwin and then he closed his bedroom door.

"Ok what I'm about to tell you has to can never get out of your mouth! What is said in this room stays, in this room. Got it?"

"Wow this must be huge!"

"Yeah it is so promise?"

"Yeah promise."

"Wait!"

Derek got up from his bed and got a note pad and a pen.

"Here. Sign here."

"What's this?"

"It's a contract. If you break this contract I will break your neck you got that?"

Edwin nodded. He signed the contract.

"Ok, I think I might like Ca…Casey!"

Edwin stared at Derek… stared and stared at him.

"Well… Say something Ed."

"You know what its ok actually because your not blood related to her and its legal to marry her."

Derek looked at Edwin.

"You're okay with this?"

"Yeah I mean as long as you're not related by blood, its ok with me."

"Yeah right I mean we're not related by blood and we aren't a real family so its ok right? Yeah it's ok."

Edwin looked at Derek and he laughed at him for not knowing such a simple thing.

High school

"Hey there klutzilla!"

"Hey there moron!"

"Ouch touché! I see someone was up all night practicing how to talk back."

Derek snickered while Casey acted like he wasn't there. Then Sam came by.

"Sup guys!"

"Hi Sam"

"Hey. Come on walk me to class."

"In a minute Derek, I wanted to ask you guys if you could come by the pizza shop by the river tonight. I have big news."

"Yeah what time?"

"Come by at 7 ok?"

Casey and Derek both nodded. Sam and Derek walked to class. Casey left to. School was over and Casey wondered why he wanted her to com to.

"Maybe he wants to hook up with me again?"

Casey was thrilled with the idea of him and her again. She searched though her closet to find what she would wear. When it was 7 she got ready. She wore a white mini skirt with a pink tank top and a pink sweater over the top. When she went downstairs, Derek looked at her with amazement. To him she was stunning.

"What Derek? You want to say something sarcastic?"

"Nothing at all uh… come on Sam's waiting at the shop."

Derek drove with Casey to the Pizza shop. He wondered why she was all dressed up.

"Why are you all dressed up?"

"Why do you care?"

"No reason just wondering…"

"Well keep wondering because I'm not telling you."

Derek stayed silent afterwards. They finally got to the store and saw Sam.

"Wow Casey you looked great!"

"Thank you."

Derek felt like puking on Sam.

"Thanks for coming. I just wanted to tell my friends the great news."

"Dude what is it?"

"Oh here she comes."

Derek and Casey turned around and saw a beautiful blonde hair girl with blue eyes and the most perfect figure. It was like a model just walked out of the bathroom. The girl came by the table and sat next to Sam. Casey frowned.

"Um… who is she?"

"She is my new girlfriend. This is the big news I wanted to tell you."

"Oh…. Well this certainly is big news."

Derek looked at Casey who looked like she was going to cry right now.

"Uh… sorry but I forgot that Emily and I had plans so see ya."

Casey ran out of the store.

"I'm going to drive Case to the movie theater"

Derek followed Casey.

"Casey, wait!"

Derek grabbed her wrists and stopped her. They both were panting.

"Why... Are you… running?"

Casey turned around. Derek Saw Casey crying. Her blue eyes were crystal clean and had tears coming down. Casey yanked her wrist back and ran again. Derek chased after her again.

"Wait!"

Casey finally stopped at the river. There was no one there… it was pitch black… the only thing you could see was the city lights. Derek stood besides her panting.

"You …. Okay now?"

Casey sat down on a rock. Derek did the same.

"Did you think that you and Sam were gonna get back together again?"

Casey nodded.

"Oh god Casey… I can't believe you thought that you were going to get back"


	2. Chapter 2

I DO NOT OWN LIFE WITH DEREK

"_Oh god Casey… I can't believe you thought that you were going to get back with him?"_

Casey looked up at Derek with her teary face. Her mascara was falling off and made her look like a monster.

"Well, I am sorry that I don't follow your dating rules." Casey yelled.

She laid her head back down on her knees and hide under her arms. Derek sighed. He saw Casey crying he didn't like it; he wanted to comfort her except nothing he thought of would comfort her.

"Casey?"

Casey looked up at Derek "Wha--"

Derek had kissed her on the lips. Casey did nothing except let him kiss her. She didn't struggle or anything, she just let him kiss her. Derek stopped kissing her and moved 3 inches away from her lips. He whispered "Sorry…" He stood up; held out his hand.

"Come on let's go home."

Casey grabbed his hand and stood up. Derek let go; walked towards his car. Casey stared at him wondering what had just happened. The car was silent. Casey looked out the window and wondered.

"_Why did he say sorry? He kissed me and all he could say was sorry?"_

Derek pulled up in the driveway; he got out of the car; went inside. Casey followed after him. They both ran up to their rooms. Casey locked herself in her room, she touched her lips.

"Why didn't I resist?"

Derek was in his room, wearing his head phones listening to music, to try and forget what had happened.

The next morning

Nora and George had gone to work early and Casey woke everyone up except Derek, who woke up early for the first time.

Edwin asked "Derek? What are you doing up so early?"

Derek looked upset "Shut up!"

Edwin did as he was told. Casey and Derek didn't speak to each other the whole day. At school, they would try to avoid each other as much as possible. During 5th period, Derek thought about Casey and what he should say towards Casey, but all he could think about was the kiss. When the bell rang, Derek ran out of class; he suddenly bumped into Kendra, the most popular girl in school.

"Sorry."

"That's ok, Derek."

Derek looked up and saw Kendra smiling. Derek picked up her books and handed it to her.

"Thanks."

"No problem. Bye."

"Wait!"

Derek turned towards Kendra.

"I want to ask you about something."

"Ok shoot."

"Want to go out with me?"

Derek looked at her, not really shocked because every girl wanted him. Derek took a moment and said "Let me think about it ok?"

Kendra nodded. Derek walked away with a sad look in his eye.

House of the MacDonald and Venturi.

Derek looked out his window and wondered if he should go out with Kendra. He knew he could never go out with Casey. He had pondered this for a long time. Then he heard a knock on his door.

"Come in."

Casey came in.

"What?"

"I wanted to talk to you about something."

Derek got scared.

"Ok shoot."

"Remember that night at the river? Where we you know, kissed?"

Derek nodded.

"Well I wanted to tell you Derek tha--"

"Listen Casey, just forget that ever happened. It didn't mean anything. It was a mistake so just forget it."

Casey looked at him with anger.

"Ok, fine."

Casey walked out of Derek's door which felt like she was walking out of his life. Casey had tears running down her eyes.

"Derek is such a jerk!"

The next day at school, Derek saw Kendra.

"Let's go out."

"I knew you would say yes."

Kendra held Derek's arm and walked to class. 

"Did you hear?"

"No what, Emily?"

"Derek and Kendra are going out!"

"What?"

"Yeah I know! I mean seriously if he wanted to go out with someone he should have picked someone better!"

Casey was shocked. Derek was going out with a girl right after he kissed her.

A week had past after Casey heard the news about Derek and Kendra. Every time, Kendra came to her house to meet Derek, she got jealous. She didn't know why, but she wanted to rip Kendra's hair and kick her in the stomach. Then she realized.

"I like Derek?"

After Casey realized that she went downstairs, to the living room. She saw Derek on his chair, watching TV. Casey took a big breath and walked down the stairs.

"Where are mom and George?"

"Out"

"Oh?"

Casey sat on the sofa next to Derek. She took a big breath and let it out.

"Derek?"

"What?"

"I think I like you."

Derek looked at her and Casey looked at him. There was silence in the room.

to be continued

If you like this then please write reviews, I would very much appreciate that. Thank you. Oh and I know that I have grammar and other mistakes so please if you see any than tell me thank you.


	3. Chapter 3

I do not own life with Derek

"_I think I like you."_

"What?"

Derek looked at Casey, shocked.

"I said I --"

"Yeah I know what you said, its just… how, why, when?"

Derek was stuttering, he couldn't think of anything else to say.

"Look, Derek I know that this is a huge thing, but I just wanted to know and you don't have to say anything. I just wanted to tell you because I don't want to hide anything from you."

Derek kept staring at her with shock. Casey got up from the couch and left. Derek finally blinked and got up from his seat fast, grabbed Casey's wrist and her waist line. He kissed her and said "Took you long enough." Derek smirked. Casey smiled and apologized "Sorry." They kissed and hugged.

Next day

"Good morning mom."

"Good morning Casey. You're in a good mood today."

"Yeah well, I feel good."

"Well that is great. I am glad that you do."

Casey smiled. Derek walked in. Casey and Derek looked at each other and than looked away smiling.

School

"Derek, wait up!"

Derek turned around to see Casey catching up.

"Man you are slow."

"So what, you love me for that anyway."

Derek smiled; held out his hand.

"Let's walk to school together."

Casey smiled; took his hand. They walked together to school.

"Derek, remember we have to keep our relationship a secret."

"Yeah I know Case."

"Good."

When they got to school, they let go of each other's hand and went their separate ways.

"Derek!"

Derek turned around hoping it was Casey, but instead it was Kendra.

"Oh…"

"Wow, you don't sound happy to see your girlfriend?"

"Oh right… listen Kendra we need to talk."

"Ok, sure."

"Let's go talk some where else."

Kendra followed Derek to a deserted science room.

"Kendra--"

"Derek, look at the tree there! It's huge! I wonder when it--"

"Kendra!"

Kendra stood silently with a scared face.

"I need to talk to you."

"Ok, so talk"

"I want to break up. I'm sorry."

"I'm sorry I didn't hear correctly. What?"

"Kendra, I know you heard me."

"Derek, I don't hear things I don't want to hear ok? You are not dumping me! Got that? What I want I get and I want you… and I got you."

"Kendra… I just don't--"

"Feel a connection? Yeah I heard that before but guess what I don't care… Derek I like you, do you know what you're doing? Every guy in school wants to go out with me and yet you choose to dump me?"

"Kendra--"

"Don't say another word! Derek I'll do you a favor and act like I didn't hear that… ok? Now my birthday is in 3 days and I want you to come to my party… we'll go shopping later ok? Bye."

"Kendra!"

Kendra left, acting like she couldn't hear Derek call after her. Derek sighed and leaned against the dusty desk; looked out the window. School was over and Casey got home first.

"Hey is Derek here?"

"No why?"

"No reason, I just didn't see him in school either."

"What did he do now?"

"Lizzie why do you think he did something to me?"

"Well, you always look for him whenever he does something to annoy you."

"Well, he didn't do anything, a teacher asked me to tell Derek something."

Casey left Lizzie and wondered where Derek was. It was 9:48 when Derek came home.

"Derek you're late."

"Sorry, I just had… things to do."

"Come on I'll warm your dinner."

"No thanks, Dad."

Derek ran to his room and grabbed his headphones to listen music on his bed.

School

"Derek!"

"What Case?"

"Can we talk?"

"Sure."

"Come on."

Casey dragged Derek to the deserted science room.

"Derek are you okay?"

"Yeah why?"

"Well, you seem tense… plus you and I haven't talked in a long time."

"Well I'm fine."

"Are you sure?"

"YES! Why are you nagging me?"

"What? I'm not nagging you."

"Yes you are… and its annoying!"

Casey started to get teary.

"Well I am sorry."

"Oh spare me the tears. Casey enough god! Why the hell are you crying huh?"

"Are you serious? You are yelling at me and asking me why I am crying?"

"Oh man… this is stupid. This is never gonna work Casey! This whole relationship is stupid! I can't believe I thought it was gonna work!"

Casey stared at him with shock.

"What? Is that how you really feel?"

"Yes!"

"Well, you don't have to worry anymore! This relationship is over!"

Casey ran out the room. Derek put his headphones over his head to take his anger out.

"Oh my gosh! Casey and Derek together like a …couple?"

(The mystery person gasped!)

to be continued

Sorry that I haven't updated in a while, uh… I hope you like this, if you do then give me good review please! Ill update more if you like! )


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